Primitive members of subg. Stylophyllum, such as Dudleya virens, have open corollas, with petals spreading from near the middle, in contrast to the prismatic or tubular corollas of subg. Dudleya. Also included in this subgenus, for want of a better place, are the tetraploid D. traskiae and two Mexican polyploids, all with campanulate, and thus intermediate, corollas. These are taken to be allopolyploids between members of subg. Dudleya and primitive members of subg. Stylophyllum. More-advanced members are those with cylindric leaves, ending with D. attenuata, which also has the most reduced inflorescence.